P2.06-01 Short-Term Outcome of Entire Pleural Intensity-Modulated Radiotherapy in a Neoadjuvant Setting for Malignant Mesothelioma

The purpose of this study is to evaluate the safety and efficacy of the tri-modality treatment with neoadjuvant intensity-modulated radiotherapy (IMRT) for a resectable clinical T1-3N0-1M0 malignant pleural mesothelioma (MPM). A total of ten malignant mesothelioma patients who received neoadjuvant radiotherapy between March 2016 and April 2018 were reviewed. Patients received 25Gy in five fractions to entire ipsilateral hemithorax including clinically suspicious lymph nodes. All patients were treated with helical tomotherapy. All of the patients were men with a median age of 60 years. Epitheloid subtype was found in nine patients (90%) and type was unknown in one patient (10%). All patients received neoadjuvant chemotherapy with Alimta-cisplatin(AP) regimen. Nine patients (90%) completed 25Gy/5fxs radiotherapy and one (10%) completed 20Gy/4fxs. IMRT was well tolerated with only one acute grade 3 radiation pneumonitis. Surgery was performed one week (1 - 15 days, median 7.5) after completing IMRT. Extrapleural pneumonectomy (EPP) was performed in three patients (30%), and pleurectomy and decortications (PD) in six (60%). There was no grade 3+ surgical complication except one patient died from septic shock after EPP in one-month. Based on operative findings and pathologic stagings, adjuvant chemotherapy was delivered in six patients (60%), and one (10%) was decided to start adjuvant radiotherapy. After a median follow-up of 10.6 months (range 1.7 - 24.2), there is no evidence of local recurrence or distant metastasis. Neoadjuvant intensity-modulated radiotherapy (IMRT) can be safely delivered with a favorable radiation complication. An optimal strategy has to be made in resectable MPM patients who would benefit from neoadjuvant radiation and surgery. Further studies need to look at long-term outcomes.